Telephone.



E. S. & C. D. STEWART.

TELEPHONE.

APPLICATION man MAY26.1913.

Patented May 11, 1915.

@ ihwosey the cup 1 and the cap o nrrnn STATES Parana? caries.

EDW'ARD SCOTT STEXRCABT AND CHRISTOPHER DGUGLASS STE\VABT, OF OTTAWA.

. ILLINOIS.

TELEPHONE.

Application filed May 26, 1913.

Be it known that we, Enwano S. STiawAn'r and 'Uiiuis'roriinu l). S'rrnvvnr, citizens of the United States, residing at Ottawa, in the county of La Salle and State of Illinois, have invented a certain new and useful linprovement in Telephones. of which the following is a full, clear, concise, and exact description, reference being had to the ac companving drawings, forming a part of this specification. 1

()ur invention relates to telephones and has for its object the provision of a combined telephone transmitter and receiver, which in the form herein shown is oi" great use as a lineman's test telephone, although of course onr invention is not to he limited to such use alone, as it has various and many armlications and may be suitably modified for further and other applications without departing from the spirit of our invention herein disclosed.

Generally speaking our invention cont-cur plates a telephone receiver having a diaphragm, which diaphragm in addition to transmitting sound waves received'hy the receiver in the form of electric unr'lu'ations', also serves as the diaphragm for a trans mitting element, which.transmitting element the diaphragm-i actuatcs by virtue of confined air within a suitable chamber.

lVe will explain one form of carrying out our invention by referring to the accompanying drawing, in which Figure 1 is a front view of a telephone constructed in accordance with our invention; Fig. '2 is a longitudinal sectional View thereof; Fig. 3 is a rear view thereof, and 4- is .1 sectional view at right angles to that of Fig. 2.

In the form herein shown ourinvention contemplates a shell or cup 1 provided with a cap 2 having screw threaded engagementvvith the cup. 'i l ithin the shell we mount a pair of magnetic pole pieces 3, 3, which carry a-receiver coil 4'. A permanent mag net forming part of the entire circumference of a circle unites the pole pieces 3, 3 so that these pole pieces together with' the permanent magnet 5 and the coils 4-. 4 form a rcceiver'in connection with the diaphragm which diaphragm is held in placelwtwccn The rear extremity of the cup 1 has an opening 7, against which opening a mica diaphragm ll placed. .\n

Specification of Letters Patent.

'lov Letters Patent Patented May 11, 1915.

annular insulating washer 8 is placed be tween an insulating cover 9 and the mica diaphragm ll, antl suitably held in place by the strip 10. and the insulating washer '5 a. mica diaphragm 11 is placed and suitably held, which mica diaphragm carries a carbon electrode 12. A. further electrode 13 is mounted in the rear of the cup 9 and between the two electrodes granular carbon 14 is placed. A transmitting element is thus formed upon the back of the receiver cup 1 and insulated therefrom. The movable electrode 12 of this transmitting element is thus in contact with the air in the confined space within the cup 1. Now whenever the diaphragm 6 is actuated by talking against it from without the device, the confined air Will be agitated, thus to vibrate this movable electrode 12 to actuate the transmitting element. Two circuit terminals 15 and 16 are provided so that the circuit extends, say from the terminal 16 by means of conductor 17 to the metal cover 9, through the transmitting element, to the electrode 12', then by means of the conductor 18 to one of the coils 4, then through the other coil 4, and then by means of the conductor 19 to the other terminal 15, the receiving and transmitting element-s thus being in series sii'nilarly to the ordinary direct current receiver. Under certain circumstances therefore, of course, the

permanent magnet 5 might be dispensed with. It will be thus seen that the dia phragm (3 serves two purposes. First to transform the electrical undulations of the coils 4 into sound waves and to actuate the transmitting element to cause electrical undulations through the interposition of the confined air within the device.

It is thought from what has been described that the operation of our improved dilwice will be clear and that it will also he clear that the particular illustration used is illustrative merely of one form of carrying out our invention.

Having however thus described this particular form of carrying out our invention. what we claim as new and desire to secure l. A device oi the character described comprising a diaphragm. an cl ctromagnotic HHH'Ll winding for a tuating will diaphragm. a variahl l($l l'fltl('l transm tting element, and an a r ronhrung cas ng to which said transmitting element and dig phragm are mounted so that said diaphragm when actuated by sound waves actua tes said transmitting element through the agency of the air confined within said-casing, said transmitting element having a fixed electrode rigidly mounted on said casing and a movable electrode, and said casing having an opening therein registering with said movable elect ode. I i

2. A device of the character described comprising a diaphragm, an electromagnetic receiver winding for actuating said diaphragm, a variable resistance transmitting element, and an air confining casing to which said transmitting element and diaphragm are mounted so that said diaphragm when actuated by'sound waves actuates said transmitting element through the agency of the air confined within said casing, said transmitting element having afixed electrode rigidly mounted on said casing and a I movable electrode, and said casing having an opening therein registering with said movable electrode and closed by said transmitting element. I

3. A device of the character described comprisinga diaphragm, an electromagnetic ireceiver winding for actuating said diahragm, a transmitting element, andan air onfining casing to which said transmitting lement and diaphragm are mounted so that said diaphragm when actuated by sound waves actuates said transmitting clement through the agency of the air confined within said casing, said transmitting element having a movable electrode and a carbon chamber provided with comminuted material, said chamber being fixedly mounted on the casing and said casing having an opening therein registering with said movable electrode and closed by said transmitting element.

4. A device of the character described comprising a casing, a diaphragm mounted on said casing, and forming a substantially air-tight compartment with said casing, a receiver magnet mounted within said casing to actuate said diaphragm, and a carbon carrying cup rigidly mounted on said casing and having a movable electrode actuated by said diaphragm through the air confined within said casing when said diaphragm is under the influence of sound waves exteriorly of said casing.

In witness whereof, we hereunto subscribe our names this seventh day of May, A. D" 1913.

EDWARD SCOTT STEWART. CHRISTOPHER DOUGLASS STEWART.

Witnesses:

P. G. 'FIHUH, OTIS M. BACK. 

